docs: def __range(a, bins):
      '''Compute the histogram range of the values in the array a according to
      scipy.stats.histogram.'''
      a = numpy.asarray(a)
      a_max = a.max()
      a_min = a.min()
      s = 0.5 * (a_max - a_min) / float(bins - 1)
      return (a_min - s, a_max + s)